Automotive Telematics System Design
In 2015, the cost of the electronics in a new car surpassed the cost of raw steel for the first time in history. We shouldn’t be surprised; the increasing number of electronic systems placed in cars over time made this change in cost structure inevitable. As cars become more autonomous, more connected, and include more creature comforts, this trend is only going to continue.
After the OnStar system was popularized by General Motors in the 1990s, automotive telematics systems have been a fixture in the industry. Today, an automotive telematics system allows manufacturers to gather data from event data recorders, communication systems, GPS navigation systems, and safety systems. Recent advancements in technology and the push for fully driverless vehicles in the future is pushing greater use of these systems, and designers should consider how they can create these systems and incorporate them into new vehicles.
The Telematics System Landscape
Revenue for automotive PCBs alone is expected to continue climbing by 5%-10% year-over-year. So what is driving growth in this area? In addition to newer safety features, infotainment systems, and interconnectivity, telematics systems are seeing greater use in conventional vehicles and will be required in future autonomous vehicles.
Telematics systems are one area where automotive electronics companies and the major auto manufacturers can see major growth as these systems will likely be required in more new conventional vehicles and autonomous vehicles. As of 2018, EU Regulation 2015/758 requires that all new vehicles sold in the EU officially include a telematics system. Different states in the US have different rules around telematics systems, but the General Services Administration officially recognizes their importance in current vehicle fleets from the perspective of cost savings.
As part of continued development of autonomous vehicles, telematics systems allow vehicle manufacturers, researchers, and insurers to gather data on these new vehicles before they are rolled out to the public. The average human driver can travel approximately 50,000 miles before they have an accident, whereas the average distance an autonomous vehicle drove as part of a DARPA Grand Challenge was approximately 100 miles. The mass of data moving throughout a vehicle can be collected with a vehicle telematics system, giving engineers the insights they need to improve their technology. This same data is also being used by insurers to create pricing plans under the usage-based insurance (UBI) model.
The eCall telematics system is now mandatory in the EU
PCBs for Telematics Systems in Vehicles
Whether you are implementing a solution for UBI insurance, driverless cars, vehicle diagnostics, automated emergency and accident response, or systems for intervehicle communication, telematics services are expected to evolve from their current applications. These changes will be reflected at the PCB level and at the embedded software level as the mass of data generated in new vehicles needs to be processed and communicated in real-time.
These systems can be integrated somewhere under the hood or in the dashboard, or they can be added as an aftermarket feature through the vehicle’s OBD-II port. In either case, this gives the device direct access to vehicle data from the vehicle’s ECU. These devices have small form factor (less than 10 cu. in.) and will run on the car’s DC power. Vehicle sensors will gather data that is stored in ECUs, which is then sent to the telematics unit for processing, storage, and transmission. One option on an aftermarket device is to include a USB port or a port for a microSIM card; this is done in the popular Freematics ONE+ system (see the schematic below).
Schematic of the Freematics ONE+ telematics system
These systems generally run at tens or hundreds of MHz clock rates and do not require extremely high-speed logic. If the telematics system will be placed under the dashboard, then you can build your board on FR4. A telematics system that is placed in the engine compartment is best built on a ceramic PCB, although this placement does not add any advantages in terms of functionality.
Including Wifi and/or Bluetooth connectivity in a telematics module allows your telematics data to be downloaded to an external device, although newer telematics modules that provide data to insurers, manufacturers, or employers need cellular access to transmit data. One option is to transmit over WCDMA, HSPA+, or other wireless protocol. No matter which protocol you use for communication, you’ll need to include a transceiver and connection to a chip (for integrated modules) or rubber-ducky antenna (typically on after-market modules).
This brings the telematics system into the mixed signal regime, which requires an RF grounding strategy. Analog and digital signals should be separated into different areas of the ground plane to prevent interference. A four layer board with a single solid ground plane usually works well for these systems, although a good strategy is to use a ground plane to provide some shielding between the RF and digital sections. Here, you’ll be running at no more than 5 GHz, depending on the wireless protocol.
Newer cars generally already include GPS navigation systems that are integrated into the infotainment system. This navigation data is already moving between the display (either infotainment or digital dashboard display) and a central ECU, and the data can be sent to the telematics unit through the OBD-II port. This really requires a software patch and possibly a modification to the OBD-II design.
For an aftermarket telematics system, the GPS antenna should be connected as an external unit through the side of the package and should be mounted in the appropriate location to receive the best signal. The top of the dashboard near the center of the windshield is an ideal spot to place the antenna, although these antennas can also be attached to the front or rear windshield while flipped over.
The Role of Embedded Software in Telematics Systems
The regulatory aspects of data privacy, particularly in the EU, will likely play a greater role at the software level rather than the hardware level. However, one can expect telematics systems to have greater minimum functionality requirements in industrialized countries as technology continues to advance. Security issues in vehicles will mirror those that arise in IoT devices as vehicles become more connected, creating real challenges for embedded software engineers. Engineers should expect scalable open software and hardware platforms to appear as smartphones and tablets become the dominant way to interact with telematics systems in vehicles.
Electronics designers in the automotive industry need access to design tools with the right PCB layout and embedded design tools for telematics systems and a variety of other systems. Altium Designer® contains design features for these automotive applications and much more, and all within a unified design environment.